Conduit and electrical conduit are tubing systems used to protect and route wiring, electrical wiring, communications wiring, and the like. Conduit may be made of metal (including iron, steel, galvanized steel, stainless steel, aluminum, bronze, and brass), plastic polymer, fiber, fired clay, and composite materials. Types of conduit include rigid metal conduit, galvanized rigid conduit, intermediate metal conduit, electrical metallic tubing, aluminum conduit, rigid nonmetallic conduit, electrical nonmetallic tubing, flexible metallic conduit, liquid-tight flexible metal conduit, flexible metallic tubing, and liquid-tight flexible nonmetallic conduit.
By way of example, conduit may comprise a metal core which is coated (potentially on both interior and exterior sides) with a corrosion resistant material, such as zinc or polyurethane. Such corrosion resistant material shall be referred to herein as “thin protective coat”. A protective layer, such as polyvinyl chloride (“PVC”) or another plastic or a polymer, may be applied to the exterior of the conduit, such as by coating the metal core (which may have also received a thin protective coat) in PVC. This protective layer is referred to herein as “external coating”. A conduit with an external coating is referred to herein as “coated conduit”.
Conduit may be unthreaded or threaded. A typical piece of threaded conduit comprises at least one male threaded end, which male threaded end is suitable to be screwed into a female threaded conduit fitting or box connector.
As used herein, “conduit fitting” shall be used to refer to “couplings”, “conduit bodies”, and “box connectors”. Couplings join two pieces of conduit together via threaded or slip connectors, into which the conduit screws or is otherwise inserted and secured. Conduit bodies join two or more pieces of conduit together via threaded or slip connectors and have an access cover to allow access to the interior of the conduit body. The access cover may be disconnected from the conduit body to expose a cavity and allow wiring or the like to be pulled through conduit which is secured to at least one side of the conduit body. When the wiring is pulled through, the access cover may then being re-connected to the conduit body to cover the cavity. Types of conduit bodies include L-shaped bodies (also referred to as “Ells”), T-shaped bodies (“Tees”), C-shaped bodies (“Cees”), and Service Ell bodies (“SLBs”). Box connectors are structures used to secure conduit to a junction box or other electrical box via a threaded connection or a compression fitting (which may be part of the box connector or may involve additional components). In the case of conduit fittings with threaded connectors, the threaded connector is typically a female receptacle which receives the male threaded conduit end.
As with conduits, conduit fittings may be coated in PVC or another plastic polymer external coating. Conduit fittings with an external coating shall be referred to herein as “coated conduit fittings”. A coated conduit fitting may comprise a sleeve at the location of the female threaded receptacle in the fitting; conduit, generally coated conduit, fits into the sleeve and may be screwed into or otherwise may be secured to the female receptacle in the coated conduit fitting. The sleeve of a coated conduit fitting generally accommodates the conduit with a tight fit which may require expansion of the sleeve. When external coating is applied to a conduit, the external coating is often applied by a party other than the party who manufactured the conduit. When external coating is applied to a conduit, markings, if any, on the conduit are frequently covered by the external coating.
As used herein, a “conduit system” comprises at least one conduit and at least one conduit fitting.
Electrical conduit systems are often installed by electricians, service professionals, and construction laborers. The installation is often in difficult to access areas of structures, attics, drop ceilings, false floors, crawl spaces, concrete structures (in which the conduit may be embedded), beams, or in underground locations such as duct banks, utility tunnels, or trenches in the ground. The conduit is often left in place for years and is subject to moisture, corrosive environmental conditions, decay and movement of the surrounding building or environment, plant and animal life, and other disturbances. For these reasons and because the conduit may protect critical infrastructure, care should be taken when conduit is installed.
Commonly, and particularly for electrical conduit systems, the conduit system must be inspected by parties such as engineers and building or construction inspectors; inspectors may have professional or governmental obligations to perform a careful inspection and to note deficiencies relative to required or desired objectives. An element in such inspections may be whether, in a conduit system, conduit has been adequately secured into conduit fittings. In the case of coated conduit fittings, the sleeve may obscure the connection site, making it difficult or impossible to tell whether the conduit has been completely screwed or inserted into the conduit fitting. In addition, the cramped, awkward, and often inaccessible or not easily viewed location of the conduit system may further make it difficult to inspect the conduit system.
Disclosed is a coated conduit end with a perceivable demarcation which quickly and reliably indicates how far conduit is screwed or inserted into a coated conduit fitting to form a conduit system.